Viruses have been shown to cause malignancy in a number of different animal systems. In recent years, members of the herpesvirus group and the oncornavirus group have been implicated in human malignancy. The purpose of this proposal is to investigate the role of the oncornaviruses in the malignant process of a single organ -- the prostate. Prostatic tissue will be obtained from patients with benign or malignant prostates, as well as from normal individuals. The tissue will be examined histologically to determine the disease state of the prostate, and will be either grown in cell culture or assayed directly for the presence of oncornaviruses or their gene products. The techniques that will be used in this study include, electron microscopy and radioactive labeling methods for the detection of complete virus particles, and gel diffusion and radioimmune assay for the detection of oncornaviral antigens. Tissues that are successfully grown as cell cultures will also be examined for the presence of oncornaviral components. In addition, attempts will be made to induce the production of oncornaviruses by the cell cultures in the event that they prove to be non-productive, using various methods in an effort to isolate a candidate human oncogenic virus. Included in this proposal is a prospective study involving patients seen by physicians in private practices of urology and oncology, that will be followed by serial bleedings over a five year period. These serum samples will be tested for the presence of specific antibodies to oncornaviral antigens, with the goal being the appearance or increase in antibody activity that coincides with the appearance of the malignant state of the prostate. The combined approach outlined in this proposal will reveal the role that oncornaviruses play in carcinoma of the human prostate.